Heretofore, numerous devices have been proposed for cleaning the driving and recording elements of cassette recorders, e.g., the capstans, rollers and heads. One of the best known of these cleaning devices is a cassette loaded with a short length of slightly abrasive cleaning tape but since this tape has a thickness much greater than that of a normal recording tape, it involves the risks of damaging or putting out of adjustment some of the tape recorder members for guiding, driving and recording/playing back the tape.
Another known cassette for cleaning contains a device actuated by one of the take-up or supply spindles (German Utility Model No. 6,928,925 of July 22, 1969 in the name of Becker Autoradiowerk GmbH), but since cassettes of this type have only one working side (take-up reel) their great disadvantages are:
(1) that they cannot be used on "bi-directional" units; bi-directional drive tape recorders are frequently equipped on each of the reels with an automatic stop device, such as described in Schatteman, U.S. Pat. No. 3,488,017 and since, in a cleaning cassette of this type the supply reel is not driven, the automatic stop device of the tape recorder immediately operates either to stop the unit or eject the cassette;
(2) that they require close attention by users when introduced into single direction drive tape recorders, since such a cleaning cassette must always be inserted in such a way that the reel hub within the cassette which actuates the cleaning elements is placed on the take-up reel spindle; if this rule is not observed, no cleaning takes place and the cleaning cassette is immediately ejected if the tape player is equipped with a mechanical stop or the tape player is switched off if it is equipped with an automatic stop device of the type described in U.S. Pat. No. 3,488,017; since most users are unaware of this kind of technical problem, they will conclude from this that their cleaning cassette is completely out of order.